backport: performance improvements for the event query API (#7319) (#9334)

* Performance improvements for the event query API (#7319)

Rework the implementation of event query parsing and execution to
improve performance and reduce memory usage.

Previous memory and CPU profiles of the pubsub service showed query
processing as a significant hotspot. While we don't have evidence that
this is visibly hurting users, fixing it is fairly easy and self-contained.

Updates #6439.

Typical benchmark results comparing the original implementation (PEG) with the reworked implementation (Custom):
```
TEST                        TIME/OP  BYTES/OP  ALLOCS/OP  SPEEDUP   MEM SAVING
BenchmarkParsePEG-12       51716 ns  526832    27
BenchmarkParseCustom-12     2167 ns    4616    17         23.8x     99.1%
BenchmarkMatchPEG-12        3086 ns    1097    22
BenchmarkMatchCustom-12    294.2 ns      64     3         10.5x     94.1%
```

libs/pubsub/query/oldquery/fuzz_test/main.go

@@ -0,0 +1,30 @@
+package fuzz_test
+
+import (
+	"fmt"
+
+	query "github.com/tendermint/tendermint/libs/pubsub/query/oldquery"
+)
+
+func Fuzz(data []byte) int {
+	sdata := string(data)
+	q0, err := query.New(sdata)
+	if err != nil {
+		return 0
+	}
+
+	sdata1 := q0.String()
+	q1, err := query.New(sdata1)
+	if err != nil {
+		panic(err)
+	}
+
+	sdata2 := q1.String()
+	if sdata1 != sdata2 {
+		fmt.Printf("q0: %q\n", sdata1)
+		fmt.Printf("q1: %q\n", sdata2)
+		panic("query changed")
+	}
+
+	return 1
+}